Note: Each collection contains 96.5k documents and each collection have these fields --
{
"name": "variable1",
"startTime": "variable2",
"endTime": "variable3",
"classes": "variable4",
"section": "variable"
}
I have 2 collections. I have to compare these 2 collection and have to find out whether some specific fields( here I want name, startTime, endTime) of the documents are same in both the collection.
My approach was to join these 2 collection and then use $lookup .. I also tried the following query but it didn't work. Please help me.
col1.aggregate([
{
"$unionWith": {"col1": "col2"}
},
{
"$group":
{
"_id":
{
"Name": "$Name",
"startTime": "$startTime",
"endTime": "$endTime"
},
"count": {"$sum": 1},
"doc": {"$first": "$$ROOT"}
}
},
{
"$match": {"$expr": {"$gt": ["$count", 1]}}
},
{
"$replaceRoot": {"newRoot": "$doc"}
},
{
"$out": "newCollectionWithDuplicates"
}
])
You're approach is fine you just have a minor syntax error in your $unionWith, it's suppose to be like so:
{
"$unionWith": {
coll: "col2",
pipeline: []
}
}